NCERT Solutions for CBSE Class 10 Physics — 311 solved questions with detailed explanations.
All measurements are taken from the pole (P) of the mirror along the principal axis:
The relationship between object distance (u), image distance (v), and focal length (f) is:
1/v + 1/u = 1/f
This formula is valid for all spherical mirrors and all positions of the object. Always use the sign convention when substituting values.
Magnification (m) tells us how much larger or smaller the image is compared to the object:
m = h'/h = -v/u
Where:
First Law: The incident ray, the refracted ray, and the normal at the point of incidence all lie in the same plane.
Second Law (Snell's Law): The ratio of the sine of the angle of incidence to the sine of the angle of refraction is constant for a given pair of media. This constant is called the refractive index.
n₁ sin i = n₂ sin r
Or equivalently: sin i / sin r = n₂ / n₁ = n₂₁
Where n₂₁ is the refractive index of medium 2 with respect to medium 1.
The absolute refractive index of a medium is the ratio of the speed of light in vacuum to the speed of light in that medium:
n = c / v
Where c = 3 × 108 m/s (speed in vacuum) and v = speed in the medium.
A higher refractive index means the medium is optically denser — light travels more slowly through it.
1/v - 1/u = 1/f
Where u = object distance, v = image distance, f = focal length. Note the minus sign — this is different from the mirror formula!
m = h'/h = v/u
Note: Unlike mirrors, there is no negative sign in front of v/u for lenses.
The power of a lens is a measure of how strongly it converges or diverges light.
P = 1/f
Where f is in metres and P is in dioptres (D).
Example: A convex lens of focal length 20 cm = 0.2 m has power P = 1/0.2 = +5 D.
When multiple thin lenses are placed in contact, the net power is the algebraic sum:
P = P₁ + P₂ + P₃ + ...
This is how opticians prescribe spectacles — they combine lens powers to achieve the exact correction needed.
Difficulty: Easy · Topic: Laws of Reflection
The first law of reflection states that the angle of incidence (∠i) is always equal to the angle of reflection (∠r). The second law states that the incident ray, reflected ray, and normal all lie in the same plane. Snell's law and the law of refraction deal with refraction, not reflection.
Difficulty: Easy · Topic: Focal length from radius of curvature
\(f = \frac{R}{2} = \frac{46}{2} = 23\) cm
Difficulty: Easy · Topic: Focal length from radius of curvature
\(f = \frac{R}{2} = \frac{55}{2} = 27\) cm
Difficulty: Easy · Topic: Focal length from radius of curvature
\(f = \frac{R}{2} = \frac{7}{2} = 3\) cm
Difficulty: Easy · Topic: Focal length from radius of curvature
\(f = \frac{R}{2} = \frac{22}{2} = 11\) cm
Difficulty: Easy · Topic: Focal length from radius of curvature
\(f = \frac{R}{2} = \frac{59}{2} = 29\) cm
Difficulty: Easy · Topic: Focal length from radius of curvature
\(f = \frac{R}{2} = \frac{35}{2} = 17\) cm
Difficulty: Easy · Topic: Focal length from radius of curvature
\(f = \frac{R}{2} = \frac{50}{2} = 25\) cm
Difficulty: Easy · Topic: Focal length from radius of curvature
\(f = \frac{R}{2} = \frac{17}{2} = 8\) cm
Difficulty: Easy · Topic: Focal length from radius of curvature
\(f = \frac{R}{2} = \frac{28}{2} = 14\) cm
Difficulty: Easy · Topic: Focal length from radius of curvature
\(f = \frac{R}{2} = \frac{8}{2} = 4\) cm
Difficulty: Easy · Topic: Focal length from radius of curvature
\(f = \frac{R}{2} = \frac{38}{2} = 19\) cm
Difficulty: Easy · Topic: Focal length from radius of curvature
\(f = \frac{R}{2} = \frac{6}{2} = 3\) cm
Difficulty: Easy · Topic: Focal length from radius of curvature
\(f = \frac{R}{2} = \frac{48}{2} = 24\) cm
Difficulty: Easy · Topic: Focal length from radius of curvature
\(f = \frac{R}{2} = \frac{19}{2} = 9\) cm
Difficulty: Easy · Topic: Focal length from radius of curvature
\(f = \frac{R}{2} = \frac{34}{2} = 17\) cm
Difficulty: Easy · Topic: Focal length from radius of curvature
\(f = \frac{R}{2} = \frac{43}{2} = 21\) cm
Difficulty: Easy · Topic: Focal length from radius of curvature
\(f = \frac{R}{2} = \frac{54}{2} = 27\) cm
Difficulty: Easy · Topic: Focal length from radius of curvature
\(f = \frac{R}{2} = \frac{57}{2} = 28\) cm
Difficulty: Easy · Topic: Focal length from radius of curvature
\(f = \frac{R}{2} = \frac{24}{2} = 12\) cm
Difficulty: Easy · Topic: Focal length from radius of curvature
\(f = \frac{R}{2} = \frac{10}{2} = 5\) cm
Difficulty: Easy · Topic: Focal length from radius of curvature
\(f = \frac{R}{2} = \frac{53}{2} = 26\) cm
Difficulty: Easy · Topic: Focal length from radius of curvature
\(f = \frac{R}{2} = \frac{21}{2} = 10\) cm
Difficulty: Easy · Topic: Focal length from radius of curvature
\(f = \frac{R}{2} = \frac{9}{2} = 4\) cm
Difficulty: Easy · Topic: Focal length from radius of curvature
\(f = \frac{R}{2} = \frac{15}{2} = 7\) cm
Difficulty: Easy · Topic: Power of a lens
Power \(= \frac{1}{f(\text{in m})} = \frac{100}{40} = 2.5\) D
Difficulty: Easy · Topic: Power of a lens
Power \(= \frac{1}{f(\text{in m})} = \frac{100}{30} = 3.33\) D
Difficulty: Easy · Topic: Power of a lens
Power \(= \frac{1}{f(\text{in m})} = \frac{100}{20} = 5.0\) D
Difficulty: Easy · Topic: Power of a lens
Power \(= \frac{1}{f(\text{in m})} = \frac{100}{25} = 4.0\) D
Difficulty: Easy · Topic: Power of a lens
Power \(= \frac{1}{f(\text{in m})} = \frac{100}{15} = 6.67\) D
Difficulty: Easy · Topic: Power of a lens
Power \(= \frac{1}{f(\text{in m})} = \frac{100}{10} = 10.0\) D
Difficulty: Easy · Topic: Power of a lens
Power \(= \frac{1}{f(\text{in m})} = \frac{100}{50} = 2.0\) D
Difficulty: Easy · Topic: Focal length from radius of curvature
\(f = \frac{R}{2} = \frac{60}{2} = 30\) cm
Difficulty: Easy · Topic: Focal length from radius of curvature
\(f = \frac{R}{2} = \frac{29}{2} = 14\) cm
Difficulty: Easy · Topic: Focal length from radius of curvature
\(f = \frac{R}{2} = \frac{14}{2} = 7\) cm
Difficulty: Easy · Topic: Focal length from radius of curvature
\(f = \frac{R}{2} = \frac{20}{2} = 10\) cm
Difficulty: Easy · Topic: Focal length from radius of curvature
\(f = \frac{R}{2} = \frac{58}{2} = 29\) cm
Difficulty: Easy · Topic: Focal length from radius of curvature
\(f = \frac{R}{2} = \frac{52}{2} = 26\) cm
Difficulty: Easy · Topic: Focal length from radius of curvature
\(f = \frac{R}{2} = \frac{11}{2} = 5\) cm
Difficulty: Easy · Topic: Focal length from radius of curvature
\(f = \frac{R}{2} = \frac{23}{2} = 11\) cm
Difficulty: Easy · Topic: Focal length from radius of curvature
\(f = \frac{R}{2} = \frac{31}{2} = 15\) cm
Difficulty: Easy · Topic: Focal length from radius of curvature
\(f = \frac{R}{2} = \frac{56}{2} = 28\) cm
Difficulty: Easy · Topic: Focal length from radius of curvature
\(f = \frac{R}{2} = \frac{12}{2} = 6\) cm
Difficulty: Easy · Topic: Focal length from radius of curvature
\(f = \frac{R}{2} = \frac{40}{2} = 20\) cm
Difficulty: Easy · Topic: Focal length from radius of curvature
\(f = \frac{R}{2} = \frac{47}{2} = 23\) cm
Difficulty: Easy · Topic: Focal length from radius of curvature
\(f = \frac{R}{2} = \frac{30}{2} = 15\) cm
Difficulty: Easy · Topic: Focal length from radius of curvature
\(f = \frac{R}{2} = \frac{27}{2} = 13\) cm
Difficulty: Easy · Topic: Focal length from radius of curvature
\(f = \frac{R}{2} = \frac{16}{2} = 8\) cm
Difficulty: Easy · Topic: Focal length from radius of curvature
\(f = \frac{R}{2} = \frac{51}{2} = 25\) cm
Difficulty: Easy · Topic: Focal length from radius of curvature
\(f = \frac{R}{2} = \frac{25}{2} = 12\) cm
Difficulty: Easy-Medium · Topic: Spherical Mirrors
A concave mirror is called a converging mirror because when parallel rays of light fall on it, they converge (come together) at the focus after reflection. A convex mirror is the diverging mirror — it spreads rays apart.
Difficulty: Easy-Medium · Topic: Spherical Mirrors
For a spherical mirror, the relationship between focal length (f) and radius of curvature (R) is:
f = R / 2
f = 30 / 2 = 15 cm
Difficulty: Easy-Medium · Topic: Convex Mirror
Convex mirrors are used as rear-view mirrors because they always form erect and diminished images. More importantly, they have a wider field of view compared to plane mirrors, allowing the driver to see a larger area of the road behind. The images are always virtual, erect, and smaller than the object.
Difficulty: Easy-Medium · Topic: Refraction
Glass is optically denser than air. When light enters a denser medium from a rarer medium, it bends toward the normal. Since the refractive index of glass (~1.5) is greater than air (~1.0), light slows down in glass. The speed of light in glass is approximately c/1.5 = 2 × 108 m/s.
Difficulty: Easy-Medium · Topic: Power of a Lens
Given: f = -50 cm = -0.5 m (negative because concave lens)
Power: P = 1/f = 1/(-0.5) = -2 D
The negative sign indicates it is a diverging (concave) lens.
Difficulty: Easy-Medium · Topic: Reflection
Regular Reflection: Occurs on smooth, polished surfaces. All reflected rays are parallel to each other, forming a clear image. Example: plane mirror, still water surface.
Diffuse Reflection: Occurs on rough, unpolished surfaces. Reflected rays scatter in different directions because the surface has micro-irregularities. Example: paper, wall, fabric.
Does diffuse reflection violate the laws of reflection?
No. Even in diffuse reflection, each individual ray obeys both laws of reflection perfectly. At each tiny point on the rough surface, the angle of incidence equals the angle of reflection. The scattering occurs because the normals at different points on the surface point in different directions due to the surface roughness.
Difficulty: Easy-Medium · Topic: Refraction
When we look at a pencil partly immersed in water, the part below the water surface appears displaced or bent. Here's why:
Light rays from the submerged part of the pencil travel from water (denser medium) to air (rarer medium). At the water-air interface, these rays bend away from the normal (refraction from denser to rarer medium).
When these refracted rays reach our eyes, our brain traces them back in straight lines. The apparent position of the submerged part of the pencil is where these extended straight lines seem to originate — which is higher than its actual position.
Since the part above water is at its true position and the part below appears shifted upward, the pencil appears to be bent or broken at the surface. This is an optical illusion caused by refraction.
Difficulty: Easy-Medium · Topic: Convex Lens
When an object is placed at the focus (F₁) of a convex lens, the refracted rays emerge parallel to the principal axis. Parallel rays never meet (or meet at infinity). Therefore, the image is formed at infinity. It is real, inverted, and highly enlarged. This is the principle behind searchlights and collimators.
Difficulty: Easy-Medium · Topic: Concave Lens
A concave lens is a diverging lens. It always diverges the rays passing through it. The diverging rays, when traced back, appear to meet on the same side as the object. This produces an image that is always virtual, erect, and diminished — regardless of where the object is placed.
Difficulty: Easy-Medium · Topic: Power of a Lens
P = 1/f (where f is in metres)
f = 1/P = 1/2 = 0.5 m = 50 cm
Since P is positive, it is a convex (converging) lens.
Difficulty: Easy-Medium · Topic: Magnification
\(m = -\frac{v}{u} = -\frac{-40}{-50} = -0.8\)
Difficulty: Easy-Medium · Topic: Magnification
\(m = -\frac{v}{u} = -\frac{-15}{-30} = -0.5\)
Difficulty: Easy-Medium · Topic: Magnification
\(m = -\frac{v}{u} = -\frac{-25}{-35} = -0.71\)
Difficulty: Easy-Medium · Topic: Magnification
\(m = -\frac{v}{u} = -\frac{40}{-24} = 1.67\)
Difficulty: Easy-Medium · Topic: Magnification
\(m = -\frac{v}{u} = -\frac{-20}{-40} = -0.5\)
Difficulty: Easy-Medium · Topic: Magnification
\(m = -\frac{v}{u} = -\frac{20}{-45} = 0.44\)
Difficulty: Easy-Medium · Topic: Magnification
\(m = -\frac{v}{u} = -\frac{-30}{-40} = -0.75\)
Difficulty: Easy-Medium · Topic: Magnification
\(m = -\frac{v}{u} = -\frac{20}{-24} = 0.83\)
Difficulty: Easy-Medium · Topic: Magnification
\(m = -\frac{v}{u} = -\frac{40}{-25} = 1.6\)
Difficulty: Easy-Medium · Topic: Magnification
\(m = -\frac{v}{u} = -\frac{40}{-30} = 1.33\)
Difficulty: Easy-Medium · Topic: Magnification
\(m = -\frac{v}{u} = -\frac{-15}{-50} = -0.3\)
Difficulty: Easy-Medium · Topic: Magnification
\(m = -\frac{v}{u} = -\frac{-15}{-40} = -0.38\)
Difficulty: Easy-Medium · Topic: Magnification
\(m = -\frac{v}{u} = -\frac{-30}{-60} = -0.5\)
Difficulty: Easy-Medium · Topic: Magnification
\(m = -\frac{v}{u} = -\frac{-60}{-50} = -1.2\)
Difficulty: Easy-Medium · Topic: Magnification
\(m = -\frac{v}{u} = -\frac{-30}{-45} = -0.67\)
Difficulty: Easy-Medium · Topic: Magnification
\(m = -\frac{v}{u} = -\frac{-40}{-24} = -1.67\)
Difficulty: Easy-Medium · Topic: Magnification
\(m = -\frac{v}{u} = -\frac{-40}{-25} = -1.6\)
Difficulty: Easy-Medium · Topic: Magnification
\(m = -\frac{v}{u} = -\frac{-30}{-24} = -1.25\)
Difficulty: Easy-Medium · Topic: Magnification
\(m = -\frac{v}{u} = -\frac{-25}{-40} = -0.62\)
Difficulty: Easy-Medium · Topic: Magnification
\(m = -\frac{v}{u} = -\frac{30}{-50} = 0.6\)
Difficulty: Easy-Medium · Topic: Magnification
\(m = -\frac{v}{u} = -\frac{20}{-50} = 0.4\)
Difficulty: Easy-Medium · Topic: Magnification
\(m = -\frac{v}{u} = -\frac{-20}{-60} = -0.33\)
Difficulty: Easy-Medium · Topic: Magnification
\(m = -\frac{v}{u} = -\frac{-60}{-30} = -2.0\)
Difficulty: Easy-Medium · Topic: Magnification
\(m = -\frac{v}{u} = -\frac{40}{-60} = 0.67\)
Difficulty: Easy-Medium · Topic: Magnification
\(m = -\frac{v}{u} = -\frac{60}{-24} = 2.5\)
Difficulty: Easy-Medium · Topic: Magnification
\(m = -\frac{v}{u} = -\frac{-30}{-50} = -0.6\)
Difficulty: Easy-Medium · Topic: Magnification
\(m = -\frac{v}{u} = -\frac{-20}{-24} = -0.83\)
Difficulty: Easy-Medium · Topic: Magnification
\(m = -\frac{v}{u} = -\frac{30}{-60} = 0.5\)
Difficulty: Easy-Medium · Topic: Magnification
\(m = -\frac{v}{u} = -\frac{-60}{-24} = -2.5\)
Difficulty: Easy-Medium · Topic: Magnification
\(m = -\frac{v}{u} = -\frac{-25}{-20} = -1.25\)
Difficulty: Easy-Medium · Topic: Magnification
\(m = -\frac{v}{u} = -\frac{60}{-50} = 1.2\)
Difficulty: Easy-Medium · Topic: Magnification
\(m = -\frac{v}{u} = -\frac{-40}{-40} = -1.0\)
Difficulty: Easy-Medium · Topic: Magnification
\(m = -\frac{v}{u} = -\frac{-25}{-45} = -0.56\)
Difficulty: Easy-Medium · Topic: Magnification
\(m = -\frac{v}{u} = -\frac{-20}{-15} = -1.33\)
Difficulty: Easy-Medium · Topic: Magnification
\(m = -\frac{v}{u} = -\frac{-30}{-15} = -2.0\)
Difficulty: Easy-Medium · Topic: Magnification
\(m = -\frac{v}{u} = -\frac{60}{-30} = 2.0\)
Difficulty: Easy-Medium · Topic: Magnification
\(m = -\frac{v}{u} = -\frac{-40}{-45} = -0.89\)
Difficulty: Easy-Medium · Topic: Magnification
\(m = -\frac{v}{u} = -\frac{30}{-24} = 1.25\)
Difficulty: Easy-Medium · Topic: Magnification
\(m = -\frac{v}{u} = -\frac{-30}{-35} = -0.86\)
Difficulty: Easy-Medium · Topic: Magnification
\(m = -\frac{v}{u} = -\frac{-25}{-24} = -1.04\)
Difficulty: Easy-Medium · Topic: Magnification
\(m = -\frac{v}{u} = -\frac{40}{-45} = 0.89\)
Difficulty: Easy-Medium · Topic: Magnification
\(m = -\frac{v}{u} = -\frac{20}{-60} = 0.33\)
Difficulty: Easy-Medium · Topic: Magnification
\(m = -\frac{v}{u} = -\frac{-60}{-25} = -2.4\)
Difficulty: Easy-Medium · Topic: Magnification
\(m = -\frac{v}{u} = -\frac{-25}{-60} = -0.42\)
Difficulty: Easy-Medium · Topic: Magnification
\(m = -\frac{v}{u} = -\frac{-20}{-35} = -0.57\)
Difficulty: Easy-Medium · Topic: Magnification
\(m = -\frac{v}{u} = -\frac{-60}{-35} = -1.71\)
Difficulty: Easy-Medium · Topic: Magnification
\(m = -\frac{v}{u} = -\frac{-30}{-20} = -1.5\)
Difficulty: Easy-Medium · Topic: Magnification
\(m = -\frac{v}{u} = -\frac{-40}{-60} = -0.67\)
Difficulty: Easy-Medium · Topic: Magnification
\(m = -\frac{v}{u} = -\frac{30}{-20} = 1.5\)
Difficulty: Easy-Medium · Topic: Magnification
\(m = -\frac{v}{u} = -\frac{-25}{-30} = -0.83\)
Difficulty: Easy-Medium · Topic: Magnification
\(m = -\frac{v}{u} = -\frac{60}{-20} = 3.0\)
Difficulty: Easy-Medium · Topic: Magnification
\(m = -\frac{v}{u} = -\frac{-60}{-45} = -1.33\)
Difficulty: Easy-Medium · Topic: Magnification
\(m = -\frac{v}{u} = -\frac{60}{-60} = 1.0\)
Difficulty: Easy-Medium · Topic: Magnification
\(m = -\frac{v}{u} = -\frac{40}{-15} = 2.67\)
Difficulty: Easy-Medium · Topic: Magnification
\(m = -\frac{v}{u} = -\frac{30}{-35} = 0.86\)
Difficulty: Easy-Medium · Topic: Magnification
\(m = -\frac{v}{u} = -\frac{-20}{-50} = -0.4\)
Difficulty: Easy-Medium · Topic: Magnification
\(m = -\frac{v}{u} = -\frac{60}{-15} = 4.0\)
Difficulty: Easy-Medium · Topic: Magnification
\(m = -\frac{v}{u} = -\frac{-30}{-30} = -1.0\)
Difficulty: Easy-Medium · Topic: Magnification
\(m = -\frac{v}{u} = -\frac{-40}{-30} = -1.33\)
Difficulty: Medium · Topic: Concave Mirror
When an object is placed between F and P of a concave mirror, the reflected rays diverge. If we extend them behind the mirror, they appear to meet, forming a virtual, erect, and enlarged image. This is the principle used in shaving mirrors and makeup mirrors.
Difficulty: Medium · Topic: Mirror Formula
Given: u = -30 cm (object is always on the left), f = -15 cm (concave mirror has negative f)
Using mirror formula:
1/v + 1/u = 1/f
1/v + 1/(-30) = 1/(-15)
1/v = -1/15 + 1/30
1/v = (-2 + 1)/30 = -1/30
v = -30 cm
The negative sign means the image is formed in front of the mirror — it is real.
Magnification:
m = -v/u = -(-30)/(-30) = -1
|m| = 1, so the image is the same size as the object. The negative sign indicates the image is inverted.
Nature: Real, inverted, same size, formed at the centre of curvature (since v = -30 cm = 2f = R).
Difficulty: Medium · Topic: Convex Mirror
Given: u = -20 cm, f = +10 cm (convex mirror has positive f)
Using mirror formula:
1/v + 1/u = 1/f
1/v + 1/(-20) = 1/10
1/v = 1/10 + 1/20 = (2 + 1)/20 = 3/20
v = +20/3 ≈ +6.67 cm
Positive v means the image is behind the mirror — it is virtual.
Magnification:
m = -v/u = -(20/3)/(-20) = +1/3 ≈ +0.33
Positive m means the image is erect. |m| < 1 means it is diminished (one-third the size).
Difficulty: Medium · Topic: Refractive Index
Given: n = 1.5, c = 3 × 108 m/s
Formula: n = c/v
Therefore: v = c/n = (3 × 108) / 1.5
v = 2 × 108 m/s
Light travels at two-thirds of its vacuum speed when passing through glass.
Difficulty: Medium · Topic: Snell's Law
The refractive index n = c/v. A refractive index of 2.42 means:
2.42 = (speed in vacuum)/(speed in diamond)
So light travels 2.42 times slower in diamond compared to vacuum. This is why diamond bends light so dramatically and sparkles brilliantly — its high refractive index causes significant bending and internal reflections.
Difficulty: Medium · Topic: Lens Formula
Given: u = -30 cm (object on left), f = +20 cm (convex lens)
Using lens formula:
1/v - 1/u = 1/f
1/v - 1/(-30) = 1/20
1/v + 1/30 = 1/20
1/v = 1/20 - 1/30 = (3 - 2)/60 = 1/60
v = +60 cm
Positive v means the image is on the right side of the lens — it is real.
Magnification: m = v/u = 60/(-30) = -2
Negative m means the image is inverted. |m| = 2 means it is twice the size of the object (enlarged).
Difficulty: Medium · Topic: Power of a Lens
Given: P = +1.5 D
Focal length: f = 1/P = 1/1.5 = +0.667 m ≈ +66.7 cm
Since the power is positive, this is a converging (convex) lens.
A positive power lens is prescribed for hypermetropia (long-sightedness), where the person has difficulty seeing nearby objects.
Difficulty: Medium · Topic: Combination of Lenses
Given: P₁ = +3.5 D, P₂ = -2.5 D
Net power: P = P₁ + P₂ = 3.5 + (-2.5) = +1 D
Focal length: f = 1/P = 1/1 = +1 m = 100 cm
The combination behaves like a converging lens (positive power) of focal length 100 cm.
Difficulty: Medium · Topic: Concave Mirror
Ray Diagram Description:
Place the object (arrow) between C and F on the principal axis of a concave mirror.
The two reflected rays meet at a point beyond C, on the same side as the object. Draw the image (inverted arrow) at this point.
Characteristics of the image:
Difficulty: Medium · Topic: Spherical Mirrors
A concave mirror is used in headlights because of a special property: when a light source is placed at the focus (F) of a concave mirror, the reflected rays emerge as a powerful parallel beam of light.
This is the reverse of what happens when parallel rays hit a concave mirror (they converge at F). By placing the bulb at F, we get the reverse — a strong, directed beam that illuminates the road ahead over long distances without scattering.
The bulb should be placed at the focus of the concave mirror. If the bulb is placed slightly above or below the focus, the beam spreads slightly, which is how low-beam/high-beam adjustments work in some headlight designs.
Difficulty: Medium · Topic: Refraction
Snell's Law: The ratio of the sine of the angle of incidence to the sine of the angle of refraction is constant for a given pair of media and for a given colour of light.
n₁ sin i = n₂ sin r
Or: sin i / sin r = n₂/n₁
Calculation:
Refractive index of glass with respect to water:
n(glass/water) = n(glass)/n(water) = 1.52/1.33 = 1.14
This means light travels 1.14 times slower in glass than in water. When light passes from water to glass, it bends toward the normal since glass is optically denser than water.
Difficulty: Medium · Topic: Mirror Formula
Mirror formula: \(\frac{1}{v} = \frac{1}{f} - \frac{1}{u}\)
\(\frac{1}{v} = \frac{1}{-10} - \frac{1}{-25}\)
\(v = -16.67\) cm
Difficulty: Medium · Topic: Mirror Formula
Mirror formula: \(\frac{1}{v} = \frac{1}{f} - \frac{1}{u}\)
\(\frac{1}{v} = \frac{1}{-30} - \frac{1}{-50}\)
\(v = -75.0\) cm
Difficulty: Medium · Topic: Mirror Formula
Mirror formula: \(\frac{1}{v} = \frac{1}{f} - \frac{1}{u}\)
\(\frac{1}{v} = \frac{1}{-14} - \frac{1}{-45}\)
\(v = -20.32\) cm
Difficulty: Medium · Topic: Mirror Formula
Mirror formula: \(\frac{1}{v} = \frac{1}{f} - \frac{1}{u}\)
\(\frac{1}{v} = \frac{1}{-30} - \frac{1}{-30}\)
\(v = infinity\) cm
Difficulty: Medium · Topic: Mirror Formula
Mirror formula: \(\frac{1}{v} = \frac{1}{f} - \frac{1}{u}\)
\(\frac{1}{v} = \frac{1}{-12} - \frac{1}{-25}\)
\(v = -23.08\) cm
Difficulty: Medium · Topic: Mirror Formula
Mirror formula: \(\frac{1}{v} = \frac{1}{f} - \frac{1}{u}\)
\(\frac{1}{v} = \frac{1}{-12} - \frac{1}{-40}\)
\(v = -17.14\) cm
Difficulty: Medium · Topic: Mirror Formula
Mirror formula: \(\frac{1}{v} = \frac{1}{f} - \frac{1}{u}\)
\(\frac{1}{v} = \frac{1}{-12} - \frac{1}{-35}\)
\(v = -18.26\) cm
Difficulty: Medium · Topic: Mirror Formula
Mirror formula: \(\frac{1}{v} = \frac{1}{f} - \frac{1}{u}\)
\(\frac{1}{v} = \frac{1}{-10} - \frac{1}{-35}\)
\(v = -14.0\) cm
Difficulty: Medium · Topic: Mirror Formula
Mirror formula: \(\frac{1}{v} = \frac{1}{f} - \frac{1}{u}\)
\(\frac{1}{v} = \frac{1}{-10} - \frac{1}{-60}\)
\(v = -12.0\) cm
Difficulty: Medium · Topic: Mirror Formula
Mirror formula: \(\frac{1}{v} = \frac{1}{f} - \frac{1}{u}\)
\(\frac{1}{v} = \frac{1}{-16} - \frac{1}{-15}\)
\(v = 240.0\) cm
Difficulty: Medium · Topic: Mirror Formula
Mirror formula: \(\frac{1}{v} = \frac{1}{f} - \frac{1}{u}\)
\(\frac{1}{v} = \frac{1}{-15} - \frac{1}{-25}\)
\(v = -37.5\) cm
Difficulty: Medium · Topic: Mirror Formula
Mirror formula: \(\frac{1}{v} = \frac{1}{f} - \frac{1}{u}\)
\(\frac{1}{v} = \frac{1}{-20} - \frac{1}{-50}\)
\(v = -33.33\) cm
Difficulty: Medium · Topic: Mirror Formula
Mirror formula: \(\frac{1}{v} = \frac{1}{f} - \frac{1}{u}\)
\(\frac{1}{v} = \frac{1}{-25} - \frac{1}{-50}\)
\(v = -50.0\) cm
Difficulty: Medium · Topic: Mirror Formula
Mirror formula: \(\frac{1}{v} = \frac{1}{f} - \frac{1}{u}\)
\(\frac{1}{v} = \frac{1}{-14} - \frac{1}{-35}\)
\(v = -23.33\) cm
Difficulty: Medium · Topic: Mirror Formula
Mirror formula: \(\frac{1}{v} = \frac{1}{f} - \frac{1}{u}\)
\(\frac{1}{v} = \frac{1}{-15} - \frac{1}{-40}\)
\(v = -24.0\) cm
Difficulty: Medium · Topic: Mirror Formula
Mirror formula: \(\frac{1}{v} = \frac{1}{f} - \frac{1}{u}\)
\(\frac{1}{v} = \frac{1}{-14} - \frac{1}{-20}\)
\(v = -46.67\) cm
Difficulty: Medium · Topic: Mirror Formula
Mirror formula: \(\frac{1}{v} = \frac{1}{f} - \frac{1}{u}\)
\(\frac{1}{v} = \frac{1}{-10} - \frac{1}{-50}\)
\(v = -12.5\) cm
Difficulty: Medium · Topic: Mirror Formula
Mirror formula: \(\frac{1}{v} = \frac{1}{f} - \frac{1}{u}\)
\(\frac{1}{v} = \frac{1}{-16} - \frac{1}{-40}\)
\(v = -26.67\) cm
Difficulty: Medium · Topic: Mirror Formula
Mirror formula: \(\frac{1}{v} = \frac{1}{f} - \frac{1}{u}\)
\(\frac{1}{v} = \frac{1}{-25} - \frac{1}{-24}\)
\(v = 600.0\) cm
Difficulty: Medium · Topic: Mirror Formula
Mirror formula: \(\frac{1}{v} = \frac{1}{f} - \frac{1}{u}\)
\(\frac{1}{v} = \frac{1}{-20} - \frac{1}{-15}\)
\(v = 60.0\) cm
Difficulty: Medium · Topic: Mirror Formula
Mirror formula: \(\frac{1}{v} = \frac{1}{f} - \frac{1}{u}\)
\(\frac{1}{v} = \frac{1}{-30} - \frac{1}{-60}\)
\(v = -60.0\) cm
Difficulty: Medium · Topic: Mirror Formula
Mirror formula: \(\frac{1}{v} = \frac{1}{f} - \frac{1}{u}\)
\(\frac{1}{v} = \frac{1}{-14} - \frac{1}{-25}\)
\(v = -31.82\) cm
Difficulty: Medium · Topic: Mirror Formula
Mirror formula: \(\frac{1}{v} = \frac{1}{f} - \frac{1}{u}\)
\(\frac{1}{v} = \frac{1}{-20} - \frac{1}{-30}\)
\(v = -60.0\) cm
Difficulty: Medium · Topic: Mirror Formula
Mirror formula: \(\frac{1}{v} = \frac{1}{f} - \frac{1}{u}\)
\(\frac{1}{v} = \frac{1}{-25} - \frac{1}{-20}\)
\(v = 100.0\) cm
Difficulty: Medium · Topic: Mirror Formula
Mirror formula: \(\frac{1}{v} = \frac{1}{f} - \frac{1}{u}\)
\(\frac{1}{v} = \frac{1}{-14} - \frac{1}{-60}\)
\(v = -18.26\) cm
Difficulty: Medium · Topic: Snell's Law
Snell's Law: \(n_1 \sin i = n_2 \sin r\)
\(1 \times \sin(55^\circ) = 1.52 \times \sin r\)
\(\sin r = \frac{\sin 55^\circ}{1.52}\)
\(r = 32.6^\circ\)
Difficulty: Medium · Topic: Snell's Law
Snell's Law: \(n_1 \sin i = n_2 \sin r\)
\(1 \times \sin(40^\circ) = 1.44 \times \sin r\)
\(\sin r = \frac{\sin 40^\circ}{1.44}\)
\(r = 26.5^\circ\)
Difficulty: Medium · Topic: Snell's Law
Snell's Law: \(n_1 \sin i = n_2 \sin r\)
\(1 \times \sin(50^\circ) = 1.33 \times \sin r\)
\(\sin r = \frac{\sin 50^\circ}{1.33}\)
\(r = 35.2^\circ\)
Difficulty: Medium · Topic: Snell's Law
Snell's Law: \(n_1 \sin i = n_2 \sin r\)
\(1 \times \sin(45^\circ) = 1.5 \times \sin r\)
\(\sin r = \frac{\sin 45^\circ}{1.5}\)
\(r = 28.1^\circ\)
Difficulty: Medium · Topic: Snell's Law
Snell's Law: \(n_1 \sin i = n_2 \sin r\)
\(1 \times \sin(55^\circ) = 1.55 \times \sin r\)
\(\sin r = \frac{\sin 55^\circ}{1.55}\)
\(r = 31.9^\circ\)
Difficulty: Medium · Topic: Snell's Law
Snell's Law: \(n_1 \sin i = n_2 \sin r\)
\(1 \times \sin(30^\circ) = 1.6 \times \sin r\)
\(\sin r = \frac{\sin 30^\circ}{1.6}\)
\(r = 18.2^\circ\)
Difficulty: Medium · Topic: Snell's Law
Snell's Law: \(n_1 \sin i = n_2 \sin r\)
\(1 \times \sin(25^\circ) = 1.55 \times \sin r\)
\(\sin r = \frac{\sin 25^\circ}{1.55}\)
\(r = 15.8^\circ\)
Difficulty: Medium · Topic: Snell's Law
Snell's Law: \(n_1 \sin i = n_2 \sin r\)
\(1 \times \sin(60^\circ) = 1.45 \times \sin r\)
\(\sin r = \frac{\sin 60^\circ}{1.45}\)
\(r = 36.7^\circ\)
Difficulty: Medium · Topic: Snell's Law
Snell's Law: \(n_1 \sin i = n_2 \sin r\)
\(1 \times \sin(60^\circ) = 1.55 \times \sin r\)
\(\sin r = \frac{\sin 60^\circ}{1.55}\)
\(r = 34.0^\circ\)
Difficulty: Medium · Topic: Snell's Law
Snell's Law: \(n_1 \sin i = n_2 \sin r\)
\(1 \times \sin(55^\circ) = 1.33 \times \sin r\)
\(\sin r = \frac{\sin 55^\circ}{1.33}\)
\(r = 38.0^\circ\)
Difficulty: Medium · Topic: Snell's Law
Snell's Law: \(n_1 \sin i = n_2 \sin r\)
\(1 \times \sin(30^\circ) = 1.55 \times \sin r\)
\(\sin r = \frac{\sin 30^\circ}{1.55}\)
\(r = 18.8^\circ\)
Difficulty: Medium · Topic: Snell's Law
Snell's Law: \(n_1 \sin i = n_2 \sin r\)
\(1 \times \sin(60^\circ) = 1.33 \times \sin r\)
\(\sin r = \frac{\sin 60^\circ}{1.33}\)
\(r = 40.6^\circ\)
Difficulty: Medium · Topic: Snell's Law
Snell's Law: \(n_1 \sin i = n_2 \sin r\)
\(1 \times \sin(30^\circ) = 1.7 \times \sin r\)
\(\sin r = \frac{\sin 30^\circ}{1.7}\)
\(r = 17.1^\circ\)
Difficulty: Medium · Topic: Snell's Law
Snell's Law: \(n_1 \sin i = n_2 \sin r\)
\(1 \times \sin(50^\circ) = 1.45 \times \sin r\)
\(\sin r = \frac{\sin 50^\circ}{1.45}\)
\(r = 31.9^\circ\)
Difficulty: Medium · Topic: Snell's Law
Snell's Law: \(n_1 \sin i = n_2 \sin r\)
\(1 \times \sin(25^\circ) = 1.52 \times \sin r\)
\(\sin r = \frac{\sin 25^\circ}{1.52}\)
\(r = 16.1^\circ\)
Difficulty: Medium · Topic: Snell's Law
Snell's Law: \(n_1 \sin i = n_2 \sin r\)
\(1 \times \sin(25^\circ) = 1.5 \times \sin r\)
\(\sin r = \frac{\sin 25^\circ}{1.5}\)
\(r = 16.4^\circ\)
Difficulty: Medium · Topic: Snell's Law
Snell's Law: \(n_1 \sin i = n_2 \sin r\)
\(1 \times \sin(25^\circ) = 1.33 \times \sin r\)
\(\sin r = \frac{\sin 25^\circ}{1.33}\)
\(r = 18.5^\circ\)
Difficulty: Medium · Topic: Snell's Law
Snell's Law: \(n_1 \sin i = n_2 \sin r\)
\(1 \times \sin(50^\circ) = 1.5 \times \sin r\)
\(\sin r = \frac{\sin 50^\circ}{1.5}\)
\(r = 30.7^\circ\)
Difficulty: Medium · Topic: Snell's Law
Snell's Law: \(n_1 \sin i = n_2 \sin r\)
\(1 \times \sin(30^\circ) = 1.5 \times \sin r\)
\(\sin r = \frac{\sin 30^\circ}{1.5}\)
\(r = 19.5^\circ\)
Difficulty: Medium · Topic: Snell's Law
Snell's Law: \(n_1 \sin i = n_2 \sin r\)
\(1 \times \sin(25^\circ) = 1.45 \times \sin r\)
\(\sin r = \frac{\sin 25^\circ}{1.45}\)
\(r = 16.9^\circ\)
Difficulty: Medium · Topic: Snell's Law
Snell's Law: \(n_1 \sin i = n_2 \sin r\)
\(1 \times \sin(40^\circ) = 1.45 \times \sin r\)
\(\sin r = \frac{\sin 40^\circ}{1.45}\)
\(r = 26.3^\circ\)
Difficulty: Medium · Topic: Snell's Law
Snell's Law: \(n_1 \sin i = n_2 \sin r\)
\(1 \times \sin(40^\circ) = 1.55 \times \sin r\)
\(\sin r = \frac{\sin 40^\circ}{1.55}\)
\(r = 24.5^\circ\)
Difficulty: Medium · Topic: Snell's Law
Snell's Law: \(n_1 \sin i = n_2 \sin r\)
\(1 \times \sin(60^\circ) = 1.7 \times \sin r\)
\(\sin r = \frac{\sin 60^\circ}{1.7}\)
\(r = 30.6^\circ\)
Difficulty: Medium · Topic: Lens formula - image distance
Lens formula: \(\frac{1}{v} - \frac{1}{u} = \frac{1}{f}\)
u = -45 cm (sign convention), f = 20 cm
\(\frac{1}{v} = \frac{1}{20} + \frac{1}{45}\)
v = 13.85 cm
Difficulty: Medium · Topic: Lens formula - image distance
Lens formula: \(\frac{1}{v} - \frac{1}{u} = \frac{1}{f}\)
u = -25 cm (sign convention), f = 25 cm
\(\frac{1}{v} = \frac{1}{25} + \frac{1}{25}\)
v = 12.5 cm
Difficulty: Medium · Topic: Lens formula - image distance
Lens formula: \(\frac{1}{v} - \frac{1}{u} = \frac{1}{f}\)
u = -60 cm (sign convention), f = 25 cm
\(\frac{1}{v} = \frac{1}{25} + \frac{1}{60}\)
v = 17.65 cm
Difficulty: Medium · Topic: Lens formula - image distance
Lens formula: \(\frac{1}{v} - \frac{1}{u} = \frac{1}{f}\)
u = -25 cm (sign convention), f = 20 cm
\(\frac{1}{v} = \frac{1}{20} + \frac{1}{25}\)
v = 11.11 cm
Difficulty: Medium · Topic: Lens formula - image distance
Lens formula: \(\frac{1}{v} - \frac{1}{u} = \frac{1}{f}\)
u = -40 cm (sign convention), f = 10 cm
\(\frac{1}{v} = \frac{1}{10} + \frac{1}{40}\)
v = 8.0 cm
Difficulty: Medium · Topic: Lens formula - image distance
Lens formula: \(\frac{1}{v} - \frac{1}{u} = \frac{1}{f}\)
u = -40 cm (sign convention), f = 20 cm
\(\frac{1}{v} = \frac{1}{20} + \frac{1}{40}\)
v = 13.33 cm
Difficulty: Medium · Topic: Lens formula - image distance
Lens formula: \(\frac{1}{v} - \frac{1}{u} = \frac{1}{f}\)
u = -35 cm (sign convention), f = 20 cm
\(\frac{1}{v} = \frac{1}{20} + \frac{1}{35}\)
v = 12.73 cm
Difficulty: Medium · Topic: Lens formula - image distance
Lens formula: \(\frac{1}{v} - \frac{1}{u} = \frac{1}{f}\)
u = -35 cm (sign convention), f = 25 cm
\(\frac{1}{v} = \frac{1}{25} + \frac{1}{35}\)
v = 14.58 cm
Difficulty: Medium · Topic: Lens formula - image distance
Lens formula: \(\frac{1}{v} - \frac{1}{u} = \frac{1}{f}\)
u = -15 cm (sign convention), f = 20 cm
\(\frac{1}{v} = \frac{1}{20} + \frac{1}{15}\)
v = 8.57 cm
Difficulty: Medium · Topic: Lens formula - image distance
Lens formula: \(\frac{1}{v} - \frac{1}{u} = \frac{1}{f}\)
u = -35 cm (sign convention), f = 12 cm
\(\frac{1}{v} = \frac{1}{12} + \frac{1}{35}\)
v = 8.94 cm
Difficulty: Medium · Topic: Lens formula - image distance
Lens formula: \(\frac{1}{v} - \frac{1}{u} = \frac{1}{f}\)
u = -15 cm (sign convention), f = 10 cm
\(\frac{1}{v} = \frac{1}{10} + \frac{1}{15}\)
v = 6.0 cm
Difficulty: Medium · Topic: Lens formula - image distance
Lens formula: \(\frac{1}{v} - \frac{1}{u} = \frac{1}{f}\)
u = -15 cm (sign convention), f = 12 cm
\(\frac{1}{v} = \frac{1}{12} + \frac{1}{15}\)
v = 6.67 cm
Difficulty: Medium · Topic: Lens formula - image distance
Lens formula: \(\frac{1}{v} - \frac{1}{u} = \frac{1}{f}\)
u = -45 cm (sign convention), f = 25 cm
\(\frac{1}{v} = \frac{1}{25} + \frac{1}{45}\)
v = 16.07 cm
Difficulty: Medium · Topic: Lens formula - image distance
Lens formula: \(\frac{1}{v} - \frac{1}{u} = \frac{1}{f}\)
u = -35 cm (sign convention), f = 10 cm
\(\frac{1}{v} = \frac{1}{10} + \frac{1}{35}\)
v = 7.78 cm
Difficulty: Medium · Topic: Lens formula - image distance
Lens formula: \(\frac{1}{v} - \frac{1}{u} = \frac{1}{f}\)
u = -50 cm (sign convention), f = 25 cm
\(\frac{1}{v} = \frac{1}{25} + \frac{1}{50}\)
v = 16.67 cm
Difficulty: Medium · Topic: Lens formula - image distance
Lens formula: \(\frac{1}{v} - \frac{1}{u} = \frac{1}{f}\)
u = -30 cm (sign convention), f = 15 cm
\(\frac{1}{v} = \frac{1}{15} + \frac{1}{30}\)
v = 10.0 cm
Difficulty: Medium · Topic: Lens formula - image distance
Lens formula: \(\frac{1}{v} - \frac{1}{u} = \frac{1}{f}\)
u = -45 cm (sign convention), f = 12 cm
\(\frac{1}{v} = \frac{1}{12} + \frac{1}{45}\)
v = 9.47 cm
Difficulty: Medium · Topic: Lens formula - image distance
Lens formula: \(\frac{1}{v} - \frac{1}{u} = \frac{1}{f}\)
u = -20 cm (sign convention), f = 12 cm
\(\frac{1}{v} = \frac{1}{12} + \frac{1}{20}\)
v = 7.5 cm
Difficulty: Medium · Topic: Lens formula - image distance
Lens formula: \(\frac{1}{v} - \frac{1}{u} = \frac{1}{f}\)
u = -35 cm (sign convention), f = 15 cm
\(\frac{1}{v} = \frac{1}{15} + \frac{1}{35}\)
v = 10.5 cm
Difficulty: Medium · Topic: Lens formula - image distance
Lens formula: \(\frac{1}{v} - \frac{1}{u} = \frac{1}{f}\)
u = -50 cm (sign convention), f = 10 cm
\(\frac{1}{v} = \frac{1}{10} + \frac{1}{50}\)
v = 8.33 cm
Difficulty: Medium · Topic: Combination of thin lenses
\(\frac{1}{f} = \frac{1}{f_1} + \frac{1}{f_2}\)
\(= \frac{1}{30} + \frac{1}{-15}\)
\(f = -30.0\) cm
Difficulty: Medium · Topic: Combination of thin lenses
\(\frac{1}{f} = \frac{1}{f_1} + \frac{1}{f_2}\)
\(= \frac{1}{10} + \frac{1}{15}\)
\(f = 6.0\) cm
Difficulty: Medium · Topic: Combination of thin lenses
\(\frac{1}{f} = \frac{1}{f_1} + \frac{1}{f_2}\)
\(= \frac{1}{15} + \frac{1}{25}\)
\(f = 9.38\) cm
Difficulty: Medium · Topic: Combination of thin lenses
\(\frac{1}{f} = \frac{1}{f_1} + \frac{1}{f_2}\)
\(= \frac{1}{15} + \frac{1}{30}\)
\(f = 10.0\) cm
Difficulty: Medium · Topic: Combination of thin lenses
\(\frac{1}{f} = \frac{1}{f_1} + \frac{1}{f_2}\)
\(= \frac{1}{20} + \frac{1}{20}\)
\(f = 10.0\) cm
Difficulty: Medium · Topic: Combination of thin lenses
\(\frac{1}{f} = \frac{1}{f_1} + \frac{1}{f_2}\)
\(= \frac{1}{10} + \frac{1}{-20}\)
\(f = 20.0\) cm
Difficulty: Medium · Topic: Combination of thin lenses
\(\frac{1}{f} = \frac{1}{f_1} + \frac{1}{f_2}\)
\(= \frac{1}{15} + \frac{1}{-50}\)
\(f = 21.43\) cm
Difficulty: Medium · Topic: Combination of thin lenses
\(\frac{1}{f} = \frac{1}{f_1} + \frac{1}{f_2}\)
\(= \frac{1}{30} + \frac{1}{30}\)
\(f = 15.0\) cm
Difficulty: Medium · Topic: Combination of thin lenses
\(\frac{1}{f} = \frac{1}{f_1} + \frac{1}{f_2}\)
\(= \frac{1}{20} + \frac{1}{15}\)
\(f = 8.57\) cm
Difficulty: Medium · Topic: Combination of thin lenses
\(\frac{1}{f} = \frac{1}{f_1} + \frac{1}{f_2}\)
\(= \frac{1}{20} + \frac{1}{-15}\)
\(f = -60.0\) cm
Difficulty: Medium · Topic: Combination of thin lenses
\(\frac{1}{f} = \frac{1}{f_1} + \frac{1}{f_2}\)
\(= \frac{1}{25} + \frac{1}{-15}\)
\(f = -37.5\) cm
Difficulty: Medium · Topic: Combination of thin lenses
\(\frac{1}{f} = \frac{1}{f_1} + \frac{1}{f_2}\)
\(= \frac{1}{25} + \frac{1}{-20}\)
\(f = -100.0\) cm
Difficulty: Medium · Topic: Combination of thin lenses
\(\frac{1}{f} = \frac{1}{f_1} + \frac{1}{f_2}\)
\(= \frac{1}{10} + \frac{1}{-50}\)
\(f = 12.5\) cm
Difficulty: Medium · Topic: Combination of thin lenses
\(\frac{1}{f} = \frac{1}{f_1} + \frac{1}{f_2}\)
\(= \frac{1}{15} + \frac{1}{10}\)
\(f = 6.0\) cm
Difficulty: Medium · Topic: Combination of thin lenses
\(\frac{1}{f} = \frac{1}{f_1} + \frac{1}{f_2}\)
\(= \frac{1}{20} + \frac{1}{-30}\)
\(f = 60.0\) cm
Difficulty: Medium · Topic: Combination of thin lenses
\(\frac{1}{f} = \frac{1}{f_1} + \frac{1}{f_2}\)
\(= \frac{1}{20} + \frac{1}{-40}\)
\(f = 40.0\) cm
Difficulty: Medium · Topic: Combination of thin lenses
\(\frac{1}{f} = \frac{1}{f_1} + \frac{1}{f_2}\)
\(= \frac{1}{20} + \frac{1}{30}\)
\(f = 12.0\) cm
Difficulty: Medium · Topic: Combination of thin lenses
\(\frac{1}{f} = \frac{1}{f_1} + \frac{1}{f_2}\)
\(= \frac{1}{10} + \frac{1}{25}\)
\(f = 7.14\) cm
Difficulty: Medium · Topic: Combination of thin lenses
\(\frac{1}{f} = \frac{1}{f_1} + \frac{1}{f_2}\)
\(= \frac{1}{25} + \frac{1}{30}\)
\(f = 13.64\) cm
Difficulty: Medium · Topic: Combination of thin lenses
\(\frac{1}{f} = \frac{1}{f_1} + \frac{1}{f_2}\)
\(= \frac{1}{10} + \frac{1}{30}\)
\(f = 7.5\) cm
Difficulty: Medium · Topic: Combination of thin lenses
\(\frac{1}{f} = \frac{1}{f_1} + \frac{1}{f_2}\)
\(= \frac{1}{15} + \frac{1}{-40}\)
\(f = 24.0\) cm
Difficulty: Medium · Topic: Combination of thin lenses
\(\frac{1}{f} = \frac{1}{f_1} + \frac{1}{f_2}\)
\(= \frac{1}{30} + \frac{1}{20}\)
\(f = 12.0\) cm
Difficulty: Medium · Topic: Combination of thin lenses
\(\frac{1}{f} = \frac{1}{f_1} + \frac{1}{f_2}\)
\(= \frac{1}{25} + \frac{1}{20}\)
\(f = 11.11\) cm
Difficulty: Medium · Topic: Mirror Formula
Mirror formula: \(\frac{1}{v} = \frac{1}{f} - \frac{1}{u}\)
\(\frac{1}{v} = \frac{1}{-8} - \frac{1}{-40}\)
\(v = -10.0\) cm
Difficulty: Medium · Topic: Mirror Formula
Mirror formula: \(\frac{1}{v} = \frac{1}{f} - \frac{1}{u}\)
\(\frac{1}{v} = \frac{1}{-10} - \frac{1}{-20}\)
\(v = -20.0\) cm
Difficulty: Medium · Topic: Mirror Formula
Mirror formula: \(\frac{1}{v} = \frac{1}{f} - \frac{1}{u}\)
\(\frac{1}{v} = \frac{1}{-15} - \frac{1}{-60}\)
\(v = -20.0\) cm
Difficulty: Medium · Topic: Mirror Formula
Mirror formula: \(\frac{1}{v} = \frac{1}{f} - \frac{1}{u}\)
\(\frac{1}{v} = \frac{1}{-18} - \frac{1}{-45}\)
\(v = -30.0\) cm
Difficulty: Medium · Topic: Mirror Formula
Mirror formula: \(\frac{1}{v} = \frac{1}{f} - \frac{1}{u}\)
\(\frac{1}{v} = \frac{1}{-20} - \frac{1}{-25}\)
\(v = -100.0\) cm
Difficulty: Medium · Topic: Mirror Formula
Mirror formula: \(\frac{1}{v} = \frac{1}{f} - \frac{1}{u}\)
\(\frac{1}{v} = \frac{1}{-18} - \frac{1}{-60}\)
\(v = -25.71\) cm
Difficulty: Medium · Topic: Mirror Formula
Mirror formula: \(\frac{1}{v} = \frac{1}{f} - \frac{1}{u}\)
\(\frac{1}{v} = \frac{1}{-18} - \frac{1}{-30}\)
\(v = -45.0\) cm
Difficulty: Medium · Topic: Mirror Formula
Mirror formula: \(\frac{1}{v} = \frac{1}{f} - \frac{1}{u}\)
\(\frac{1}{v} = \frac{1}{-15} - \frac{1}{-45}\)
\(v = -22.5\) cm
Difficulty: Medium · Topic: Mirror Formula
Mirror formula: \(\frac{1}{v} = \frac{1}{f} - \frac{1}{u}\)
\(\frac{1}{v} = \frac{1}{-25} - \frac{1}{-60}\)
\(v = -42.86\) cm
Difficulty: Medium · Topic: Mirror Formula
Mirror formula: \(\frac{1}{v} = \frac{1}{f} - \frac{1}{u}\)
\(\frac{1}{v} = \frac{1}{-15} - \frac{1}{-30}\)
\(v = -30.0\) cm
Difficulty: Medium · Topic: Mirror Formula
Mirror formula: \(\frac{1}{v} = \frac{1}{f} - \frac{1}{u}\)
\(\frac{1}{v} = \frac{1}{-10} - \frac{1}{-30}\)
\(v = -15.0\) cm
Difficulty: Medium · Topic: Mirror Formula
Mirror formula: \(\frac{1}{v} = \frac{1}{f} - \frac{1}{u}\)
\(\frac{1}{v} = \frac{1}{-16} - \frac{1}{-25}\)
\(v = -44.44\) cm
Difficulty: Medium · Topic: Mirror Formula
Mirror formula: \(\frac{1}{v} = \frac{1}{f} - \frac{1}{u}\)
\(\frac{1}{v} = \frac{1}{-18} - \frac{1}{-35}\)
\(v = -37.06\) cm
Difficulty: Medium · Topic: Mirror Formula
Mirror formula: \(\frac{1}{v} = \frac{1}{f} - \frac{1}{u}\)
\(\frac{1}{v} = \frac{1}{-30} - \frac{1}{-35}\)
\(v = -210.0\) cm
Difficulty: Medium · Topic: Mirror Formula
Mirror formula: \(\frac{1}{v} = \frac{1}{f} - \frac{1}{u}\)
\(\frac{1}{v} = \frac{1}{-14} - \frac{1}{-30}\)
\(v = -26.25\) cm
Difficulty: Medium · Topic: Mirror Formula
Mirror formula: \(\frac{1}{v} = \frac{1}{f} - \frac{1}{u}\)
\(\frac{1}{v} = \frac{1}{-8} - \frac{1}{-60}\)
\(v = -9.23\) cm
Difficulty: Medium · Topic: Mirror Formula
Mirror formula: \(\frac{1}{v} = \frac{1}{f} - \frac{1}{u}\)
\(\frac{1}{v} = \frac{1}{-18} - \frac{1}{-50}\)
\(v = -28.13\) cm
Difficulty: Medium · Topic: Mirror Formula
Mirror formula: \(\frac{1}{v} = \frac{1}{f} - \frac{1}{u}\)
\(\frac{1}{v} = \frac{1}{-20} - \frac{1}{-35}\)
\(v = -46.67\) cm
Difficulty: Medium · Topic: Mirror Formula
Mirror formula: \(\frac{1}{v} = \frac{1}{f} - \frac{1}{u}\)
\(\frac{1}{v} = \frac{1}{-15} - \frac{1}{-35}\)
\(v = -26.25\) cm
Difficulty: Medium · Topic: Mirror Formula
Mirror formula: \(\frac{1}{v} = \frac{1}{f} - \frac{1}{u}\)
\(\frac{1}{v} = \frac{1}{-18} - \frac{1}{-40}\)
\(v = -32.73\) cm
Difficulty: Medium · Topic: Mirror Formula
Mirror formula: \(\frac{1}{v} = \frac{1}{f} - \frac{1}{u}\)
\(\frac{1}{v} = \frac{1}{-16} - \frac{1}{-45}\)
\(v = -24.83\) cm
Difficulty: Medium · Topic: Mirror Formula
Mirror formula: \(\frac{1}{v} = \frac{1}{f} - \frac{1}{u}\)
\(\frac{1}{v} = \frac{1}{-15} - \frac{1}{-50}\)
\(v = -21.43\) cm
Difficulty: Medium · Topic: Mirror Formula
Mirror formula: \(\frac{1}{v} = \frac{1}{f} - \frac{1}{u}\)
\(\frac{1}{v} = \frac{1}{-10} - \frac{1}{-15}\)
\(v = -30.0\) cm
Difficulty: Medium · Topic: Mirror Formula
Mirror formula: \(\frac{1}{v} = \frac{1}{f} - \frac{1}{u}\)
\(\frac{1}{v} = \frac{1}{-18} - \frac{1}{-24}\)
\(v = -72.0\) cm
Difficulty: Medium · Topic: Mirror Formula
Mirror formula: \(\frac{1}{v} = \frac{1}{f} - \frac{1}{u}\)
\(\frac{1}{v} = \frac{1}{-20} - \frac{1}{-60}\)
\(v = -30.0\) cm
Difficulty: Medium · Topic: Mirror Formula
Mirror formula: \(\frac{1}{v} = \frac{1}{f} - \frac{1}{u}\)
\(\frac{1}{v} = \frac{1}{-12} - \frac{1}{-15}\)
\(v = -60.0\) cm
Difficulty: Medium · Topic: Mirror Formula
Mirror formula: \(\frac{1}{v} = \frac{1}{f} - \frac{1}{u}\)
\(\frac{1}{v} = \frac{1}{-16} - \frac{1}{-35}\)
\(v = -29.47\) cm
Difficulty: Medium · Topic: Mirror Formula
Mirror formula: \(\frac{1}{v} = \frac{1}{f} - \frac{1}{u}\)
\(\frac{1}{v} = \frac{1}{-8} - \frac{1}{-35}\)
\(v = -10.37\) cm
Difficulty: Medium · Topic: Mirror Formula
Mirror formula: \(\frac{1}{v} = \frac{1}{f} - \frac{1}{u}\)
\(\frac{1}{v} = \frac{1}{-14} - \frac{1}{-40}\)
\(v = -21.54\) cm
Difficulty: Medium · Topic: Mirror Formula
Mirror formula: \(\frac{1}{v} = \frac{1}{f} - \frac{1}{u}\)
\(\frac{1}{v} = \frac{1}{-16} - \frac{1}{-30}\)
\(v = -34.29\) cm
Difficulty: Medium · Topic: Snell's Law
Snell's Law: \(n_1 \sin i = n_2 \sin r\)
\(1 \times \sin(35^\circ) = 1.6 \times \sin r\)
\(\sin r = \frac{\sin 35^\circ}{1.6}\)
\(r = 21.0^\circ\)
Difficulty: Medium · Topic: Snell's Law
Snell's Law: \(n_1 \sin i = n_2 \sin r\)
\(1 \times \sin(50^\circ) = 1.52 \times \sin r\)
\(\sin r = \frac{\sin 50^\circ}{1.52}\)
\(r = 30.3^\circ\)
Difficulty: Medium · Topic: Snell's Law
Snell's Law: \(n_1 \sin i = n_2 \sin r\)
\(1 \times \sin(55^\circ) = 1.7 \times \sin r\)
\(\sin r = \frac{\sin 55^\circ}{1.7}\)
\(r = 28.8^\circ\)
Difficulty: Medium · Topic: Snell's Law
Snell's Law: \(n_1 \sin i = n_2 \sin r\)
\(1 \times \sin(35^\circ) = 1.45 \times \sin r\)
\(\sin r = \frac{\sin 35^\circ}{1.45}\)
\(r = 23.3^\circ\)
Difficulty: Medium · Topic: Snell's Law
Snell's Law: \(n_1 \sin i = n_2 \sin r\)
\(1 \times \sin(55^\circ) = 1.5 \times \sin r\)
\(\sin r = \frac{\sin 55^\circ}{1.5}\)
\(r = 33.1^\circ\)
Difficulty: Medium · Topic: Snell's Law
Snell's Law: \(n_1 \sin i = n_2 \sin r\)
\(1 \times \sin(55^\circ) = 1.45 \times \sin r\)
\(\sin r = \frac{\sin 55^\circ}{1.45}\)
\(r = 34.4^\circ\)
Difficulty: Medium · Topic: Snell's Law
Snell's Law: \(n_1 \sin i = n_2 \sin r\)
\(1 \times \sin(45^\circ) = 1.44 \times \sin r\)
\(\sin r = \frac{\sin 45^\circ}{1.44}\)
\(r = 29.4^\circ\)
Difficulty: Medium · Topic: Snell's Law
Snell's Law: \(n_1 \sin i = n_2 \sin r\)
\(1 \times \sin(25^\circ) = 1.7 \times \sin r\)
\(\sin r = \frac{\sin 25^\circ}{1.7}\)
\(r = 14.4^\circ\)
Difficulty: Medium · Topic: Snell's Law
Snell's Law: \(n_1 \sin i = n_2 \sin r\)
\(1 \times \sin(35^\circ) = 1.7 \times \sin r\)
\(\sin r = \frac{\sin 35^\circ}{1.7}\)
\(r = 19.7^\circ\)
Difficulty: Medium · Topic: Snell's Law
Snell's Law: \(n_1 \sin i = n_2 \sin r\)
\(1 \times \sin(45^\circ) = 1.6 \times \sin r\)
\(\sin r = \frac{\sin 45^\circ}{1.6}\)
\(r = 26.2^\circ\)
Difficulty: Medium · Topic: Snell's Law
Snell's Law: \(n_1 \sin i = n_2 \sin r\)
\(1 \times \sin(40^\circ) = 1.33 \times \sin r\)
\(\sin r = \frac{\sin 40^\circ}{1.33}\)
\(r = 28.9^\circ\)
Difficulty: Medium · Topic: Snell's Law
Snell's Law: \(n_1 \sin i = n_2 \sin r\)
\(1 \times \sin(35^\circ) = 1.52 \times \sin r\)
\(\sin r = \frac{\sin 35^\circ}{1.52}\)
\(r = 22.2^\circ\)
Difficulty: Medium · Topic: Snell's Law
Snell's Law: \(n_1 \sin i = n_2 \sin r\)
\(1 \times \sin(40^\circ) = 1.7 \times \sin r\)
\(\sin r = \frac{\sin 40^\circ}{1.7}\)
\(r = 22.2^\circ\)
Difficulty: Medium · Topic: Snell's Law
Snell's Law: \(n_1 \sin i = n_2 \sin r\)
\(1 \times \sin(45^\circ) = 1.45 \times \sin r\)
\(\sin r = \frac{\sin 45^\circ}{1.45}\)
\(r = 29.2^\circ\)
Difficulty: Medium · Topic: Snell's Law
Snell's Law: \(n_1 \sin i = n_2 \sin r\)
\(1 \times \sin(60^\circ) = 1.44 \times \sin r\)
\(\sin r = \frac{\sin 60^\circ}{1.44}\)
\(r = 37.0^\circ\)
Difficulty: Medium · Topic: Snell's Law
Snell's Law: \(n_1 \sin i = n_2 \sin r\)
\(1 \times \sin(40^\circ) = 1.52 \times \sin r\)
\(\sin r = \frac{\sin 40^\circ}{1.52}\)
\(r = 25.0^\circ\)
Difficulty: Medium · Topic: Snell's Law
Snell's Law: \(n_1 \sin i = n_2 \sin r\)
\(1 \times \sin(35^\circ) = 1.55 \times \sin r\)
\(\sin r = \frac{\sin 35^\circ}{1.55}\)
\(r = 21.7^\circ\)
Difficulty: Medium · Topic: Snell's Law
Snell's Law: \(n_1 \sin i = n_2 \sin r\)
\(1 \times \sin(45^\circ) = 1.55 \times \sin r\)
\(\sin r = \frac{\sin 45^\circ}{1.55}\)
\(r = 27.1^\circ\)
Difficulty: Medium · Topic: Snell's Law
Snell's Law: \(n_1 \sin i = n_2 \sin r\)
\(1 \times \sin(50^\circ) = 1.6 \times \sin r\)
\(\sin r = \frac{\sin 50^\circ}{1.6}\)
\(r = 28.6^\circ\)
Difficulty: Medium · Topic: Snell's Law
Snell's Law: \(n_1 \sin i = n_2 \sin r\)
\(1 \times \sin(30^\circ) = 1.52 \times \sin r\)
\(\sin r = \frac{\sin 30^\circ}{1.52}\)
\(r = 19.2^\circ\)
Difficulty: Medium · Topic: Snell's Law
Snell's Law: \(n_1 \sin i = n_2 \sin r\)
\(1 \times \sin(40^\circ) = 1.5 \times \sin r\)
\(\sin r = \frac{\sin 40^\circ}{1.5}\)
\(r = 25.4^\circ\)
Difficulty: Medium · Topic: Lens formula - image distance
Lens formula: \(\frac{1}{v} - \frac{1}{u} = \frac{1}{f}\)
u = -50 cm (sign convention), f = 12 cm
\(\frac{1}{v} = \frac{1}{12} + \frac{1}{50}\)
v = 9.68 cm
Difficulty: Medium · Topic: Lens formula - image distance
Lens formula: \(\frac{1}{v} - \frac{1}{u} = \frac{1}{f}\)
u = -25 cm (sign convention), f = 10 cm
\(\frac{1}{v} = \frac{1}{10} + \frac{1}{25}\)
v = 7.14 cm
Difficulty: Medium · Topic: Lens formula - image distance
Lens formula: \(\frac{1}{v} - \frac{1}{u} = \frac{1}{f}\)
u = -60 cm (sign convention), f = 20 cm
\(\frac{1}{v} = \frac{1}{20} + \frac{1}{60}\)
v = 15.0 cm
Difficulty: Medium · Topic: Lens formula - image distance
Lens formula: \(\frac{1}{v} - \frac{1}{u} = \frac{1}{f}\)
u = -20 cm (sign convention), f = 20 cm
\(\frac{1}{v} = \frac{1}{20} + \frac{1}{20}\)
v = 10.0 cm
Difficulty: Medium · Topic: Lens formula - image distance
Lens formula: \(\frac{1}{v} - \frac{1}{u} = \frac{1}{f}\)
u = -40 cm (sign convention), f = 15 cm
\(\frac{1}{v} = \frac{1}{15} + \frac{1}{40}\)
v = 10.91 cm
Difficulty: Medium · Topic: Lens formula - image distance
Lens formula: \(\frac{1}{v} - \frac{1}{u} = \frac{1}{f}\)
u = -60 cm (sign convention), f = 10 cm
\(\frac{1}{v} = \frac{1}{10} + \frac{1}{60}\)
v = 8.57 cm
Difficulty: Medium · Topic: Lens formula - image distance
Lens formula: \(\frac{1}{v} - \frac{1}{u} = \frac{1}{f}\)
u = -60 cm (sign convention), f = 12 cm
\(\frac{1}{v} = \frac{1}{12} + \frac{1}{60}\)
v = 10.0 cm
Difficulty: Medium · Topic: Lens formula - image distance
Lens formula: \(\frac{1}{v} - \frac{1}{u} = \frac{1}{f}\)
u = -20 cm (sign convention), f = 25 cm
\(\frac{1}{v} = \frac{1}{25} + \frac{1}{20}\)
v = 11.11 cm
Difficulty: Medium · Topic: Lens formula - image distance
Lens formula: \(\frac{1}{v} - \frac{1}{u} = \frac{1}{f}\)
u = -30 cm (sign convention), f = 12 cm
\(\frac{1}{v} = \frac{1}{12} + \frac{1}{30}\)
v = 8.57 cm
Difficulty: Medium · Topic: Lens formula - image distance
Lens formula: \(\frac{1}{v} - \frac{1}{u} = \frac{1}{f}\)
u = -45 cm (sign convention), f = 10 cm
\(\frac{1}{v} = \frac{1}{10} + \frac{1}{45}\)
v = 8.18 cm
Difficulty: Medium · Topic: Lens formula - image distance
Lens formula: \(\frac{1}{v} - \frac{1}{u} = \frac{1}{f}\)
u = -25 cm (sign convention), f = 12 cm
\(\frac{1}{v} = \frac{1}{12} + \frac{1}{25}\)
v = 8.11 cm
Difficulty: Medium · Topic: Lens formula - image distance
Lens formula: \(\frac{1}{v} - \frac{1}{u} = \frac{1}{f}\)
u = -30 cm (sign convention), f = 10 cm
\(\frac{1}{v} = \frac{1}{10} + \frac{1}{30}\)
v = 7.5 cm
Difficulty: Medium · Topic: Lens formula - image distance
Lens formula: \(\frac{1}{v} - \frac{1}{u} = \frac{1}{f}\)
u = -50 cm (sign convention), f = 15 cm
\(\frac{1}{v} = \frac{1}{15} + \frac{1}{50}\)
v = 11.54 cm
Difficulty: Medium · Topic: Lens formula - image distance
Lens formula: \(\frac{1}{v} - \frac{1}{u} = \frac{1}{f}\)
u = -15 cm (sign convention), f = 25 cm
\(\frac{1}{v} = \frac{1}{25} + \frac{1}{15}\)
v = 9.38 cm
Difficulty: Medium · Topic: Lens formula - image distance
Lens formula: \(\frac{1}{v} - \frac{1}{u} = \frac{1}{f}\)
u = -20 cm (sign convention), f = 15 cm
\(\frac{1}{v} = \frac{1}{15} + \frac{1}{20}\)
v = 8.57 cm
Difficulty: Medium · Topic: Lens formula - image distance
Lens formula: \(\frac{1}{v} - \frac{1}{u} = \frac{1}{f}\)
u = -20 cm (sign convention), f = 10 cm
\(\frac{1}{v} = \frac{1}{10} + \frac{1}{20}\)
v = 6.67 cm
Difficulty: Medium · Topic: Combination of thin lenses
\(\frac{1}{f} = \frac{1}{f_1} + \frac{1}{f_2}\)
\(= \frac{1}{10} + \frac{1}{-15}\)
\(f = 30.0\) cm
Difficulty: Medium · Topic: Combination of thin lenses
\(\frac{1}{f} = \frac{1}{f_1} + \frac{1}{f_2}\)
\(= \frac{1}{30} + \frac{1}{25}\)
\(f = 13.64\) cm
Difficulty: Medium · Topic: Combination of thin lenses
\(\frac{1}{f} = \frac{1}{f_1} + \frac{1}{f_2}\)
\(= \frac{1}{15} + \frac{1}{-20}\)
\(f = 60.0\) cm
Difficulty: Medium · Topic: Combination of thin lenses
\(\frac{1}{f} = \frac{1}{f_1} + \frac{1}{f_2}\)
\(= \frac{1}{20} + \frac{1}{-50}\)
\(f = 33.33\) cm
Difficulty: Medium · Topic: Combination of thin lenses
\(\frac{1}{f} = \frac{1}{f_1} + \frac{1}{f_2}\)
\(= \frac{1}{15} + \frac{1}{-30}\)
\(f = 30.0\) cm
Difficulty: Medium · Topic: Combination of thin lenses
\(\frac{1}{f} = \frac{1}{f_1} + \frac{1}{f_2}\)
\(= \frac{1}{25} + \frac{1}{25}\)
\(f = 12.5\) cm
Difficulty: Medium · Topic: Combination of thin lenses
\(\frac{1}{f} = \frac{1}{f_1} + \frac{1}{f_2}\)
\(= \frac{1}{10} + \frac{1}{-30}\)
\(f = 15.0\) cm
Difficulty: Medium · Topic: Combination of thin lenses
\(\frac{1}{f} = \frac{1}{f_1} + \frac{1}{f_2}\)
\(= \frac{1}{25} + \frac{1}{-40}\)
\(f = 66.67\) cm
Difficulty: Medium · Topic: Combination of thin lenses
\(\frac{1}{f} = \frac{1}{f_1} + \frac{1}{f_2}\)
\(= \frac{1}{30} + \frac{1}{-20}\)
\(f = -60.0\) cm
Difficulty: Medium · Topic: Combination of thin lenses
\(\frac{1}{f} = \frac{1}{f_1} + \frac{1}{f_2}\)
\(= \frac{1}{25} + \frac{1}{10}\)
\(f = 7.14\) cm
Difficulty: Medium · Topic: Combination of thin lenses
\(\frac{1}{f} = \frac{1}{f_1} + \frac{1}{f_2}\)
\(= \frac{1}{30} + \frac{1}{15}\)
\(f = 10.0\) cm
Difficulty: Medium · Topic: Combination of thin lenses
\(\frac{1}{f} = \frac{1}{f_1} + \frac{1}{f_2}\)
\(= \frac{1}{30} + \frac{1}{-30}\)
\(f = infinity\) cm
Difficulty: Medium · Topic: Combination of thin lenses
\(\frac{1}{f} = \frac{1}{f_1} + \frac{1}{f_2}\)
\(= \frac{1}{20} + \frac{1}{25}\)
\(f = 11.11\) cm
Difficulty: Medium · Topic: Combination of thin lenses
\(\frac{1}{f} = \frac{1}{f_1} + \frac{1}{f_2}\)
\(= \frac{1}{10} + \frac{1}{20}\)
\(f = 6.67\) cm
Difficulty: Medium · Topic: Combination of thin lenses
\(\frac{1}{f} = \frac{1}{f_1} + \frac{1}{f_2}\)
\(= \frac{1}{30} + \frac{1}{-40}\)
\(f = 120.0\) cm
Difficulty: Medium · Topic: Combination of thin lenses
\(\frac{1}{f} = \frac{1}{f_1} + \frac{1}{f_2}\)
\(= \frac{1}{10} + \frac{1}{10}\)
\(f = 5.0\) cm
Difficulty: Medium · Topic: Combination of thin lenses
\(\frac{1}{f} = \frac{1}{f_1} + \frac{1}{f_2}\)
\(= \frac{1}{20} + \frac{1}{-20}\)
\(f = infinity\) cm
Difficulty: Medium-Hard · Topic: Mirror Formula
Given: h = 5 cm, u = -20 cm, f = -15 cm
Step 1: Find v using mirror formula
1/v + 1/u = 1/f
1/v + 1/(-20) = 1/(-15)
1/v = -1/15 + 1/20
1/v = (-4 + 3)/60 = -1/60
v = -60 cm
Negative v means the image is formed 60 cm in front of the mirror — it is real.
Step 2: Find magnification and image height
m = -v/u = -(-60)/(-20) = -3
h' = m × h = -3 × 5 = -15 cm
The negative sign of h' means the image is inverted (below the principal axis).
Answer: The image is formed 60 cm in front of the mirror, is 15 cm tall, real, inverted, and 3 times enlarged.
Difficulty: Medium-Hard · Topic: Lens Formula
Given: h = 4 cm, u = -16 cm, f = +24 cm
Note: The object is placed between F and O (u < f), so we expect a virtual image.
Step 1: Lens formula
1/v - 1/u = 1/f
1/v - 1/(-16) = 1/24
1/v + 1/16 = 1/24
1/v = 1/24 - 1/16 = (2 - 3)/48 = -1/48
v = -48 cm
Negative v means the image is on the same side as the object — it is virtual.
Step 2: Magnification and image size
m = v/u = (-48)/(-16) = +3
h' = m × h = 3 × 4 = +12 cm
Positive m and positive h' mean the image is erect. The image is 12 cm tall — 3 times enlarged.
Nature: Virtual, erect, enlarged, on the same side as the object.
Difficulty: Medium-Hard · Topic: Mirror Formula
Given: u = -10 cm, m = -3 (real image is inverted, so m is negative for 3× magnification)
Step 1: Find v using magnification
m = -v/u
-3 = -v/(-10)
-3 = v/10
v = -30 cm
Negative v confirms the image is real (in front of the mirror).
Step 2: Find f using mirror formula
1/v + 1/u = 1/f
1/(-30) + 1/(-10) = 1/f
-1/30 - 1/10 = 1/f
(-1 - 3)/30 = 1/f
-4/30 = 1/f
f = -30/4 = -7.5 cm
The focal length is 7.5 cm. The negative sign confirms it is a concave mirror.
Difficulty: Medium-Hard · Topic: Mirror Formula
Given: h = 5 cm, u = -10 cm, R = +30 cm (convex mirror)
f = R/2 = +30/2 = +15 cm
Step 1: Mirror formula
1/v + 1/u = 1/f
1/v + 1/(-10) = 1/15
1/v = 1/15 + 1/10 = (2 + 3)/30 = 5/30 = 1/6
v = +6 cm
Positive v means image is behind the mirror — virtual.
Step 2: Magnification and image height
m = -v/u = -(6)/(-10) = +0.6
h' = m × h = 0.6 × 5 = +3 cm
Positive m and h' confirm the image is erect. |m| < 1 so it is diminished.
Answer: Virtual, erect image formed 6 cm behind the mirror, 3 cm tall.
Difficulty: Medium-Hard · Topic: Lens Formula
Given: u = -15 cm, f = -10 cm (concave lens has negative f)
Lens formula:
1/v - 1/u = 1/f
1/v - 1/(-15) = 1/(-10)
1/v + 1/15 = -1/10
1/v = -1/10 - 1/15 = (-3 - 2)/30 = -5/30 = -1/6
v = -6 cm
Negative v for a lens means the image is on the same side as the object — it is virtual.
Magnification:
m = v/u = (-6)/(-15) = +0.4
Positive m means the image is erect. |m| = 0.4 < 1, so the image is diminished (40% of original size).
Difficulty: Hard · Topic: Lens Formula
Given: f₁ = +25 cm = +0.25 m (convex), f₂ = -10 cm = -0.10 m (concave)
Power of individual lenses:
P₁ = 1/f₁ = 1/0.25 = +4 D
P₂ = 1/f₂ = 1/(-0.10) = -10 D
Net power:
P = P₁ + P₂ = 4 + (-10) = -6 D
Focal length of combination:
f = 1/P = 1/(-6) = -0.1667 m = -16.67 cm
Since the net power is negative, the combination acts as a diverging (concave) lens. The concave lens dominates because its power magnitude (10 D) exceeds that of the convex lens (4 D).
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